Technical Field
The present invention relates generally to the field of mechanical transmission for power transfer applications, and more specifically to a planetary gear drive system for reversing rotation. The present invention also generally relates to robust and compact planetary gear drive systems comprising non-metal components, such as the planet gears, that allow slippage so as to reduce or eliminate damage to the planetary drive system or the motor driving the planetary drive system. The present invention further generally relates to lighter weight planetary gear drive systems that comprise non-metal bearings, that do not require lubricants, and that can be used as an underdrive, overdrive, speed reducer, or reverse drive for motor vehicles, such as motorcycles.
Prior Art
Current mechanical transmissions generally require a lubricant. In current mechanical transmissions, gears may be meshed to drive one or more teeth against a push surface on each gear. Generally, these gears rely on a close mesh created by pitch and angle to achieve motion. These gears often and generally preferably require grease or oil or a lubricant and close tolerances to prevent excessive wear and heat stress. These gears require sturdy heavy cases to contain the gear and shafting and also hold the gears at the correct spacing to avoid heat and damage. These efforts are bulky, heavy, and generally require lubricants that can harm the environment. For example, some current transmissions require a sump for oil to pool and be pitched up for splash or pressure lubricants. Other current transmissions require grease for the gears, but the grease will degrade or its chemistry will change from heat and evaporation over time. Still other current transmissions require an oil or lubricant pump to circulate the oil or lubricant about the transmission, which pump adds bulk and weight to the device. Thus, there is a need for a lubricant-free transmission, and for a relatively light-weight lubricant-free transmission.
Current planetary gear sets suitable for use on motor vehicles generally require metal components that are relatively heavy and that do not allow for flexure or slippage without damaging the transmission. For example, robust planetary gear sets require metal gears, including the ring gear, the sun gear, and the planet gears. Although planetary gear sets can be made from non-metal materials, such non-metal sets typically are not as robust as metal sets and typically cannot be used in motor vehicles or in other applications where a significant amount of power is to be transferred through or by the planetary gear set. Further, in all-metal planetary gear sets, there can be no slippage among the gears, as the metal components will not yield relative to each other. This can prevent the sets from operating in certain desired manners, and also can result in the binding or breaking of the gears if an opposite or angular force is placed on the gear set. Thus, there is a need for a planetary gear set for use on a motor vehicle, and for other applications, that can satisfactorily use non-metal components so as to allow slippage of the gears when necessary or desired to prevent damage to the planetary gear set and drive system.
Current mechanical transmissions for motor vehicles such as motorcycles typically do not include a reverse drive. Motorcycles, motor-tricycles, motor-scooters, and the like typically do not have reverse gears, instead relying on the rider to physically push the vehicle backwards. While some such motor vehicles do have a reverse drive, it often is a separate reverse motor, apart from the primary transmission, adding bulk and weight to the motor vehicle. As such motor vehicles increase in size or as riders of such motor vehicles increase in age, or both, or just for convenience, there is a need for a robust, light-weight reverse drive or gear set suitable for use on such motor vehicles.
Some representative current mechanical transmissions include U.S. Pat. No. 6,457,381, which describes using steel gears actuated to run off a starter motor which allows the motor to turn a drive shaft backwards and the wheels in reverse. The gears cannot act as an overdrive or under drive. European Patent Application No. EP 1088178 A2 describes a steel geared transmission lubricated by oil to achieve an overdrive effect by adding an additional gear. U.S. Pat. No. 4,189,960A describes an under drive transmission using steel gears and placed behind an existing transmission. This transmission only can be operated as an under drive and from one side as input and the other as output, and requires lubrication and precise gear pitch and settings.
Accordingly, there is a need for a device for the mechanical transmission of power that solves in whole or in part the deficiencies of existing devices for the mechanical transmission of power, such as described above, and for other power transmission and motion transmission devices. It is to these needs and others that the present invention is directed.